Research suggests that synaptic and neuronal damage precedes the hair cell damage that causes increased pure-tone thresholds. The neural synapses and fibres sensitive to this type of noise-induced damage are responsible for the coding of mid- to high-intensity stimuli and seem to play a crucial role for our ability to perceive sound stimuli in background noise. Signs of a disorder impairing only supra-threshold processing without affecting pure-tone thresholds have been documented in humans before and is recently referred to as the “hidden hearing loss”. The main symptoms related to these are difficulties with speech perception in noise and presence of tinnitus despite normal pure-tone thresholds.

This project is aimed at investigating noise-induced neural degeneration in human listeners with normal pure-tone sensitivity and clarify the relation between people with a history of working in noise exposure and supra-threshold auditory impairments. It will be investigated if a history of noise exposure can be linked to the diagnosis of hidden hearing loss. Objective electrophysiological measures will be applied to investigate auditory neural firing activity. Behavioral psychoacoustic experiments will be implemented to investigate supra-threshold processing deficits. A second goal of this project is to explore the potential contribution of noise-induced neural degeneration in populations with a diagnosed high-frequency hearing loss and explore potential alternative amplification strategies for this group.